Magnetic position detection device

Abstract

A magnetic position detection device that can detect position even if there is only one object magnet. A magnetic position detection device includes a bias magnet, a magnetic detection element, an object magnet, and a mobile object. Opposite poles of the bias magnet and of the object magnet face each other. The magnetic detection element is disposed between pole surfaces of the bias magnet and of the object magnet. The magnetic detection element is fixed to the bias magnet and has a fixed positional relationship to the bias magnet. The orientation of the magnetic field at the magnetic detection element changes in accordance with the position of the object magnet. The magnetic detection element detects the orientation of the magnetic field applied to the magnetic detection element.

1 . A magnetic position detection device comprising:
 a bias magnet producing a bias magnetic field;   an object magnet producing an object magnetic field; and   a magnetic detection element detecting direction of an applied magnetic field applied to the magnetic detection element, wherein
 movement of the object magnet relative to the bias magnet changes magnetic field direction the applied magnetic field that is applied to the magnetic detection element, and, 
 when the bias magnet and the object magnet come closest to each other, the object magnetic field produced by the object magnet is larger than the bias magnetic field produced by the bias magnet at the magnetic detection element. 
   
     
     
         2 . The magnetic position detection device according to  claim 1 , wherein
 the bias magnet has two magnetic poles of opposite magnetic polarity,   the object magnet has two magnetic poles of opposite magnetic polarity, and   when the bias magnet is directly opposite the object magnet, magnetic poles of the same polarity of the bias magnet and the object magnet face each other.   
     
     
         3 . The magnetic position detection device according to  claim 1 , wherein
 the bias magnet has a magnetic pole surface having a first magnetic polarity facing the object magnet,   the object magnet has a magnetic pole surface having a first magnetic polarity facing the bias magnet,   the magnetic pole surfaces of the bias magnet and of the object magnet are substantially parallel to each other and are substantially parallel to direction of the movement of the object magnet relative to the bias magnet, and   the first polarities of the bias magnet and of the object magnet are the same polarity.   
     
     
         4 . The magnetic position detection device according to  claim 1 , wherein
 the bias magnet has a magnetic pole surface having a first magnetic polarity facing the object magnet,   the object magnet has a magnetic pole surface having a first magnetic polarity facing the bias magnet,   the magnetic pole surfaces of the bias magnet and of the object magnet are substantially parallel to each other and are substantially parallel to direction of the movement of the object magnet relative to the bias magnet, and   the first polarities of the bias magnet and of the object magnet are different from each other.   
     
     
         5 . The magnetic position detection device according to  claim 1 , wherein
 the bias magnet has a magnetic pole surface,   the object magnet has a magnetic pole surface, and   the magnetic pole surfaces of the bias magnet and of the object magnet are substantially parallel to each other and are substantially perpendicular to direction of the movement of the object magnet relative to the bias magnet.   
     
     
         6 . The magnetic position detection device according to  claim 1 , wherein
 the bias magnet has a magnetic pole surface,   the object magnet has a magnetic pole surface, and   the magnetic pole surfaces of the bias magnet and of the object magnet are substantially perpendicular to each other.   
     
     
         7 . A magnetic position detection device comprising:
 a bias magnet;   an object magnet facing the bias magnet such that different magnetic poles of the bias magnet and of the object magnet face each other; and   a magnetic detection element detecting direction of an applied magnetic field that is applied to the magnetic detection element, wherein movement of the object magnet relative to the bias magnet changes magnetic field direction of the applied magnetic field that is applied to at the magnetic detection element.   
     
     
         8 . The magnetic position detection device according to  claim 7 , wherein
 the bias magnet has a magnetic pole surface having a length, and   the object magnet has a magnetic pole surface having a length related to the direction of the movement of the object magnet relative to the bias magnet and longer than the length of the magnetic pole surface of the bias magnet.   
     
     
         9 . The magnetic position detection device according to  claim 1 , wherein position of the object magnet relative to the bias magnet is uniquely identifiable. 
     
     
         10 . The magnetic position detection device according to  claim 1 , wherein the magnetic detection element is located at a position that is closer to the object magnet than to the bias magnet when the bias magnet is directly opposite the object magnet. 
     
     
         11 . The magnetic position detection device according to  claim 1 , including only one object magnet. 
     
     
         12 . A magnetic position detection device comprising:
 a bias magnet;   a soft magnetic body; and   a magnetic detection element detecting direction of an applied magnetic field that is applied to the magnetic detection element, wherein
 movement of the soft magnetic body relative to the bias magnet changes magnetic field direction of the applied magnetic field that is applied to the magnetic detection element, and 
 position of the soft magnetic body relative to the bias magnet is uniquely identifiable. 
   
     
     
         13 . The magnetic position detection device according to  claim 7 , wherein position of the object magnet relative to the bias magnet is uniquely identifiable. 
     
     
         14 . The magnetic position detection device according to  claim 7 , wherein the magnetic detection element is located at a position that is closer to the object magnet than to the bias magnet when the bias magnet is directly opposite the object magnet. 
     
     
         15 . The magnetic position detection device according to  claim 7 , including only one object magnet.